This project is concerned with discovering brain areas important for odor-guided social discriminations and stereotyped responses to odors. Several issues are being addressed simultaneously with this line of research. First of all, the work is interested in differentiating the neural mechanisms that control reflexive responses to social odors from those that control more knowledge-based discriminatory abilities. Secondly, the present research focuses on how different types of information are extracted from communicatory signals. That is, this research asks if different types of social discrimination depend on different areas of the brain. Thirdly, the research here focuses on individual discrimination via odors as a form of naturalistic learning and memory task. The approach taken in these studies is to lesion specific neural structures (orbital cortex, mediodorsal thalamic nucleus, lateral entorhinal cortex, and cortical amygdala) that receive olfactory information and to assess possible deficits in individual and sex odor discrimination as well as odor-elicited scent marking behavior. It is expected that lesions to orbital cortex, mediodorsal thalamic nucleus and lateral entorhinal cortex will eliminate a hamster's ability to discriminate individually distinctive odors but will not affect sex-odor discriminations or odor-elicited scent marking. Conversely, lesions to the amygdala are expected to impair sex-odor discrimination and scent marking but not individual discrimination.